Cancer – Causes and prevention

Allen Weissby Allen Weiss, MD, MBA, FACP, FACR
President and CEO, NCH Healthcare System

Cancer is the second leading cause of death in America, with 1.6 million new cancer cases and 600,000 deaths from cancer predicted to occur in 2016. These statistics are from “A Cancer Journal for Clinicians” which also identified a decrease in cancer mortality of nearly 18 percent from 1969 to 2013.

Cancer is most likely a combination of diseases with many different causes. The cause and cure remain frustratingly elusive, with recent suggestions that random mutations during stem cell divisions are the major contributor to human cancer.

Science magazine this past January suggested that tissues in the human body that are more prone to develop cancer are much more likely to have a far higher total number of divisions of the normal self-renewing cells. This higher rate of turnover increases the chances of something going wrong in the control of the reproduction mechanism with the subsequent inability to turn off the reproduction of cells, namely cancer. The article goes on to suggest that only a third of the variation in cancer risk among tissues is attributable to environmental factors or inherited factors.

Certainly there is evidence that various parts of the human body have widely different rates of developing cancer. But there is also strong epidemiological evidence that lifestyle factors are important in cancer development. Most likely, just as cancer is a combination of diseases, there are combinations of causes— ranging from bad luck due to excessive cell turnover to bad lifestyle choices.

Bad luck, namely random mutations during stem cell division, is not preventable at the present time. Earlier detection and treatment helps ameliorate the effects of bad luck and certainly the medical profession is working diligently to accelerate early diagnosis and broaden effective treatment.

This past spring another influential study entitled, “Preventable Incidence and Mortality of Carcinoma Associated With Lifestyle Factors Among White Adults in the United States,” suggested that roughly half of all cancer deaths could be avoided by doing four things. (The reason for “white adults” is that this was a retrospective study combining lifestyle data from the Nurses’ Health Study and the Health Professionals Follow-up Study and there were not enough others to reach statistical significance.) Nonetheless, there is every indication that everyone benefits without regard to race, gender, or ethnicity when good lifestyle factors are embraced. The four factors: Quitting smoking, cutting back on alcohol consumption, maintaining a healthy weight, and exercising regularly. These steps could reduce the number of cancer deaths by half and reduce the number of new cancer diagnosis by as much as 70 percent.

We as a nation—and more importantly as individuals—can and should change our behavior for the better to decrease the  chances of being afflicted with cancer. Better personal behavior will also decrease the incidence of heart disease, diabetes, arthritis, mental illness, and other afflictions.


Number One on the list is always avoiding the use of tobacco. Since 1955, when the association between smoking and lung cancer was first discovered at Roswell Park Memorial Institute by Dr. Morton L. Levine, the cause of about 90 percent of lung cancer has been known. The tobacco industry’s conspiracy to deceive was challenged in a Federal lawsuit subsequently and, with time, the rate of smoking in America has dropped from 42 percent to the current 15 percent.

I had the privilege and pleasure of working with Dr. Levine at the end of his career and the beginning of mine when I was a National Science Summer Program student. Many people believe Dr. Levine might have been a Nobel Prize recipient had it not been for the tobacco industry’s effective pro-smoking marketing campaign. (Think about the Marlboro Man, Virginia Slims or the slogan “I’d walk a mile for a Camel” challenging the rationality of our nation.)

The rate of kicking the habit has recently accelerated, with the most current year showing the biggest one-year decrease of three
percent. A new concern is the emergence of electronic cigarettes whose medical risks are as yet unknown. Also it is unclear if electronic cigarettes are helping people quit, or hooking a younger population onto nicotine and subsequently other tobacco products.

Time will tell, but it would be tragic in many ways for the use of tobacco in any form to become more common.


If you don’t drink alcohol, don’t start. If you do drink, there is significant evidence that limiting consumption to one drink per day for a woman or man over age 65 and two drinks per day under 65 is considered moderate and probably not harmful. There is some evidence that this amount of alcohol can actually be helpful. In four of the five communities around the world where more people live to be 100, one of the nine common factors is drinking red wine while socializing at the end of the day before dinner.

Please note that the size of the drink matters. The absolute alcohol content of one 12-ounce beer, a 5-ounce glass of wine or 1.5-ounce mixed drink are roughly equivalent. Alcohol consumption has also been called “wasteful calories,” which gets us to the
next common evil.


Having a BMI between 18.5 and 27.5 also has been shown to be associated with a lower incidence of cancer. BMI is calculated as the ratio between height and weight, and can easily be found on the internet. Although not a perfect measure because some people can be extremely muscular, it is an easy metric to follow over time.

More than 60 percent of Americans are overweight, obese, or morbidly obese and we are now second only to Mexico as the
fattest nation in the history of civilization.  Making the healthy choice the easiest choice has proven to be beneficial for entire communities. Restaurants, grocery stores, schools, homeowner associations, and faith-based communities have all benefited their patrons, shoppers, students, residents, and congregations by offering healthier choices. The Blue Zones Project in southwest Florida has been sharing locally the successful experiences of 26 other communities. We have made good objective progress already, as the most recent Healthways- Gallup poll identified Collier County as the “Healthiest and Happiest Community” in the nation.


Weekly aerobic physical activity—defined as at least 75 vigorous intensity or 150 moderate-intensity minutes per week—is the last of the big four attributes to decrease the incidence of cancer.

Walking about five miles per day or 10,000 steps meets the Surgeon General’s recommendation for 30 minutes of moderate
activity per day. Walking is just as effective as running, but takes about twice as long to accomplish the same results. Beginners
should break the walking into smaller increments of 3-10 minutes per day. Just starting is the hardest part. Lacing up your sneakers breaks the ice. Having a friend to chat with along the way is a remarkably effective exercise tip to help sustain this good behavior.


Not much can yet be done for the bad luck of having some cells in our body going haywire. But vigilance, early diagnosis, and appropriate therapy can really make a difference for the better. Helping all of us live a longer, happier, and healthier life by at least decreasing the chances of developing cancer is a worthwhile goal and not that difficult. Because it is just as easy to learn and sustain good habits as it is bad ones.


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